Siva-1,as a p53-inducible gene,has been shown to induce extensive apoptosis in a number of different cell lines.Recent evidence suggests that Siva-1 functions as a part of the auto-regulatory feedback loop that restrains p53 through facilitating Mdm2-mediated p53 degradation.Also,Siva-1 plays an important role in suppressing tumor metastasis.Here we review the current understanding of Siva-1-mediated apoptotic signaling pathway.We also add comments on the p53-Siva-1 feedback loop,the novel function of Siva-1 in suppressing tumor metastasis,and their potential implications.